The invention is based on a wiper arm. Known windshield wipers have a wiper arm, which is made up of a fastening element and a hinge element, which is pivotably connected to it via a swivel joint and has a wiper rod. A hooklike end of the wiper rod engages a suspension box of a wiper blade, which is formed by two side cheeks of a middle bracket and includes a hinge bolt. The hinge thus formed guides the wiper blade over the vehicle window during the swiveling motion. The wiper blade has what is as a rule a multi-member support bracket system, with subordinate brackets pivotably connected to the middle bracket, at least some of which subordinate brackets, with claws on their ends, retain a wiper strip by its head strip. The multi-member support bracket system and spring rails placed in the head strip make it possible during wiping for the wiper strip to adapt, with a uniform contact pressure, to a curved windshield. To that end, a tension spring prestresses the swivel joint. The wiper arm is secured with its fastening element on a drive shaft and is driven by it in the wiping motion.
Such windshield wipers are known, for instance from German Patent Disclosure DE 37 44 237 A1. In simple versions, subordinate brackets, also known as intermediate brackets and claw brackets, can be dispensed with. In the simplest case, the middle bracket itself has claws, with which it retains the wiper strip.
Windshield washing systems for vehicles are as a rule used in conjunction with windshield wipers. They are actuated if the moisture from precipitation does not suffice to clean the vehicle window. They include a water container, spray nozzles, and a pump which pumps water, sometimes admixed with cleaning and antifreeze agents, under pressure out of the water container to the spray nozzles. As a rule, the spray nozzles are secured to some part of a vehicle body, such as a hood, window frame, or the like. To prevent the spray nozzles from freezing at temperatures below the freezing point, heating elements are integrated into the spray nozzles and communicate with a power supply via plugs located on the outside. The heating elements require relatively great effort and expense for producing the spray nozzles and great effort and expense for assembly for laying the electric lines and contacting the plugs.
It is already known for spray nozzles to be secured as additional components to the wiper blade and thus for the spray water to be distributed over the wiping region directly with a short length of stream. Since the spray water is concentrated on a region in the vicinity of the wiper blade and is washed off again within the shortest possible time by the wiping motion, the view is hindered only briefly by the spray water applied. One disadvantage of such systems is that the effects of weather, especially hail and strong sunshine, greatly affect the flexible parts of this arrangement, which are needed for spanning the hinged regions between the wiper arm and the wiper blade. Furthermore, the spray nozzles and water lines, which are exposed to the relative wind, rapidly freeze closed at temperatures below the freezing points, unless antifreeze is admixed with the water. Frozen water lines and spray nozzles can be defrosted again as a rule only with great effort.
In an earlier German Patent Application, DE 198 15 171.3, a wiper arm is described on the hinge part of which, or a wiper rod integrally connected to the hinge part, spray nozzles are disposed. The spray nozzles are located in a nozzle body, which is accommodated in a bulge of the hinge part that has an injection opening for the spray stream, or is clipped, protruding downward, in a lateral mount on the wiper rod. It is also possible for two nozzle bodies to be provided, which are joined to one another by means of a rigid or flexible connecting piece. The nozzle bodies are easily replaced and are well protected from environmental factors.
Expediently, the spray nozzle has a check valve opening outward, which prevents the water line, if the washing system has not been used for a long time, from running empty and prevents water from escaping if the wipers are operated without the washing function, especially at high wiping frequencies and/or in the case of stroke-controlled wiper arms. There is also the risk that windshield washer fluid will evaporate in the region of the spray nozzle, especially if the spray nozzle is heated, and the spray nozzle will become constricted or plugged by deposits.
A heating device, passed in the form of a wire through a water supply line and embodied as a heating coil in the nozzle body, is integrated into windshield wiper system. The heating device fits only one type of windshield wipers, so that a large number of different heating devices have to be kept on hand. Furthermore, simple solutions are obtained by providing that the nozzle bodies are integrally joined together and are produced from plastic as an injection-molded part. By means of the nozzle bodies distributed along the wiper arm, the spray water is well distributed over the wiping region, especially if a spray stream is directed into a lower region directly in front of the wiper blade. Since this arrangement results in short stream lengths, the relative wind can have only little effect on spray water distribution, even at a relatively high vehicle speed.
According to the invention, a nozzle body with one inlet conduit and at least one outlet conduit is let into a housing. The inlet conduit originates on a face end pointing toward the water inlet and discharges at a jacket face of the nozzle body, while the outlet conduit originates at the jacket face spaced apart from the inlet conduit and discharges into a spray conduit leading to the spray nozzle. A diaphragm in the pressureless state closes the inlet conduit and the outlet conduit. The outlet conduit can be located close to the spray nozzle, so that only a small volume of water is stored between the diaphragm and the spray nozzle and hence can flow or evaporate uncontrollably.
The diaphragm is embodied as an annular spring diaphragm or advantageously, in a simple way, as a rubber- elastic tubular diaphragm, which has beads on its ends. These beads are embedded in annular grooves of the nozzle body. When water flows in on the inlet side, the diaphragm is widened, opens the inlet conduit and the outlet conduit, and is braced on the outside of the housing.
In order that only the ambient pressure and the prestressing of the diaphragm have to be overcome for the sake of opening, there is a venting bore on the nozzle housing. The opening pressure of the diaphragm is slight, and so the system can be operated with a relatively small pumping capacity.
The nozzle body can easily be produced from plastic by injection molding. Its outside diameter decreases between the annular grooves on both ends, so that the tubular diaphragm is retained sealingly on its ends between the housing and the nozzle body, but in the region of the inlet conduit and the outlet conduit has sufficient radial play to open up sufficiently large flow cross sections. The smooth, cylindrical outer contour is thus preserved. To enable aiming the spray nozzle, this nozzle has a spherical outer contour, with which it is pressed into a ball seat of the nozzle body. This embodiment of the nozzle body offers the advantage of a compact design and thus lower costs.
To make the spray nozzle and the valve usable for winter operation as well, they are heated. The heating line advantageously leads through the water inlet and through a bore of the nozzle body as far as the vicinity of the spray nozzle. The heating line is soldered, glued or clamped into the nozzle body. The diaphragm closes off the water chamber from the outside and thus prevents the heated water from evaporating and calcifying the spray nozzles.
With the aid of the diaphragm, the water is trapped in the system during nonusage periods. Thus the windshield washer fluid can be sprayed in front of the wiper blade at the correct moment, in clocked spraying. In order not to hinder the view of the driver, the water sprays during the upward motion of the wiper arms, but in downward wiping no water is allowed to dribble after it.
A smaller structural volume of the entire valve is obtained by providing that the water and energy supplies are integrated in one element, and electrical contacting of the heating and the nozzle are omitted.
In this valve, good energy transmission is achieved because there is only a slight distance between the water conduit and the spray nozzle, or the spray nozzle is disposed in the conduit. When the nozzle body is made of plastic, thermal insulation from the outside is obtained, so that the heat dissipation is concentrated in particular on the spray nozzle and the water. This leads to lower energy consumption.
The heated water improves the cleaning action, so that the water consumption and especially the consumption of environmentally harmful additives can be reduced. The cleaning action can also be improved by a plurality of spray nozzles that are disposed on the wiper arm, spaced apart by several centimeters from one another.